1. Field of the invention
This invention relates to an automatic transferring system for a portable closed container, in which articles to be transferred from equipment to equipment are set in the portable closed container, which is moved by an automated guided vehicle (hereinafter referred to "AGV", when applicable) having a container interface
2. Related Art
For instance, semiconductor equipments are manufactured in a clean room, the atmosphere in which has been purified. When semiconductor wafers are transferred between processing equipments or during inter-bay transferring in such a clean room, in order to prevent the sticking of particle onto the semiconductor wafers, the semiconductor wafers are put in a portable closed container 40 as shown in FIG. 9.
In FIG. 9, reference numeral 41 designates a container body; 42A, a flange defining the opening 42 of the container body 41; 43, a handle; 44, a hollow bottom lid; and 45A and 45B, sealing members. The bottom lid 44 has a locking/unlocking mechanism as shown in FIG. 10. In FIG. 10, reference numeral 45 designates a cam; 46, a plate-shaped lock arm having a rolling element 46a, the lock arm being cantilevered in such a manner that it is longitudinally movable; 47, fulcrum members; and 48, a spring. Further in FIG. 10, reference numeral 49 designates a cam shaft extended from a lifting stand 50 which forms a container interface (described later). The cam shaft 49 is spline-engaged with the cam 45. The lifting stand 50 incorporates a cam shaft drive mechanism 51 adapted to turn the cam shaft 49 through a predetermined angle. The lock arm 46 is engaged with a recess 42B, which is formed in the inner surface of the opening 42 of the container body 41. Referring back to FIG. 9, semiconductor wafers W are stored in a cassette 52.
FIG. 11 shows one example of a conventional automatic transferring system using a closed container of this type in a clean room.
In FIG. 11, reference numeral 1 designates an LIM (linear induction motor) type inter-bay transferring line; 11 through 14, wafer processing equipments such as a CVD equipment and a film forming equipment; 20, a stocker; and 30, an automated guided vehicle (hereinafter referred to "AGV", when applicable) having an article handling robot 31.
In the system, the AGV 30 receives the closed container 40, in which wafers to be processed have been set, from the stocker 20 with the aid of the robot 31, and then moves to deliver the closed container 40 to one of the wafer processing equipments 11 through 14. Furthermore, the AGV 30 receives the cassette, in which wafers processed have been stored, from the wafer processing equipment with the aid of the robot 31, and carries it over to the stocker 20. At the wafer processing equipment, the cassette is automatically taken out of the closed container 40, and then moved, for instance, to a CVD furnace (not shown), and the cassette, in which wafers processed have been stored, is automatically taken into the closed container 40. For this purpose, each of the wafer processing equipments is provided with means (the aforementioned container interface) for automatically taking a cassette in or out of a closed container.
As indicated in FIG. 11, the wafer processing equipments 11 through 14 have stands A, where the container interfaces are built, respectively. At each wafer processing equipment, the closed container 40 is placed on the stand A coaxially with an opening B formed in it (see FIG. 9).
As was described above, in the conventional system, the wafer processing equipments 11 through 14 having a CVD furnace, a diffusing furnace, etc. and washing equipments have the container interfaces, respectively. Hence, those equipments are unavoidably bulky, and high in manufacturing cost.
In a wafer processing equipment adapted to process a number of wafers for batch processing, empty closed containers must be handled suitably, and it is necessary to provide a space for it. For instance in the case of a diffusing furnace for processing 100 wafers, four empty closed containers are necessary because, in general, one cassette accommodates twenty-five wafers.
The clean room is considerably high in constructing cost and in running cost. Therefore, if the wafer processing equipments are bulky, then the resultant semiconductor wafers are greatly increased in manufacturing cost.